There is a clinical need for devices that encapsulate living cells and allow transplantation into a host without triggering a robust immune response from the host. In general, cellular material harvested from one animal and implanted in another, even of the same species, will be attacked and destroyed by the host's immune response. In the case of organ transplants, immunosuppressive drugs are needed to prevent organ rejection. Otherwise, organ and tissue transplantation would almost always cause an immune response and result in destruction of the transplanted tissue.
However, it is possible to construct a device to encapsulate tissue or cells to eliminate the need for immunosuppressive drugs. Such a device typically is constructed of porous material allowing for the necessary exchange of metabolites, nutrients and waste products between the cell and the host. At the same time, the porosity of the material is controlled to isolate the interior of the device from invasion from the host immune system, including phagocytes.
After the device is loaded with living cells, it is implanted into a host body. It is important that the vasculature of the host grows into intimate contact with the exterior surface of the device so that blood vessels can facilitate the exchange of metabolites with the encapsulated cells through perfusion. The transplanted living cells must be in close proximity to the host blood vessels to ensure their continued survival and functioning. Therefore, loading of the cells within the device so that the cells are in proximity to the blood vessels is of primary importance. Additionally, loading of the cells must be carried out in a manner that minimizes trauma to the cells so that therapeutic amounts of the cells survive loading into the device.
Another factor to be considered in cell loading is that, in current practices, significant manual manipulation of the immune-isolation device (“IID”) in an “open” sterile environment using aseptic sterile techniques is required. Although this open air environment is sterile, manual manipulation of the IID under these conditions is undesirable due to the increased risk of contamination by unwanted microorganisms.
Therefore, there is a need for a loading fixture and method for loading that ensures the desired placement of the cells within the device and minimizes trauma to the cells while reducing or substantially eliminating the manual manipulation of the IID thereby reducing the risk of contamination of the implantable device.